Angiogenesis, the process of developing a hemovascular network from pre-existing blood vessels, is essential for the growth of solid tumors and is a component of normal wound healing and growth processes. It also has been implicated in the pathophysiology of many diseases and conditions, including atherogenesis, arthritis, psoriasis, corneal neo-vascularization, and diabetic retinopathy. Angiogenesis factors play an important role in the development of malignancies.
Tumor Endothelial Marker 8 (TEM8), also known as Anthrax Toxin Receptor 1 (ANTXR1), is a single pass, cell surface glycoprotein originally identified, along with a number of other unrelated Tumor Endothelial Markers, based on its over-expression in the endothelial cells that line the tumor vasculature of human colorectal cancer. TEM8 also functions as a cell surface receptor for Anthrax toxin, and shares 58% amino acid identity with CMG2 (also known as ANTXR2), a second receptor for Anthrax toxin protein. Unlike VEGF, VEGFRs, and many other key angiogenesis regulators, TEM8 is not required for developmental angiogenesis, wound healing or normal physiological angiogenesis of the corpus luteum. TEM8 is up-regulated on tumor vessels of various tumor types in both mice and humans, and, in some tumors, is also expressed by the tumor cells. A need exists for chemotherapeutic agents that target TEM8, and for high affinity antibodies that specifically bind TEM8 on the cell surface.